The use of complimentary/alternative medicine has become popular as evidenced by grocery store aisles and "infomercials" devoted to herbal products. These products are often misconstrued as safe because of their natural origin. With an increase in the consumption of these products, physicians need to be aware of their potential adverse effects. There are several popular over-the-counter herbal products that can affect one's behavior, especially resulting in acute mania and/or psychosis. This article provides an overview of existing literature regarding the increased use of herbal agents, reviews several case reports describing a potential association between herbal products (St. John's Wort and ginseng) and the development of mania and psychosis, and discusses the limitations in determining the frequency of serious adverse effects due to herbal products.